Bone grows through the processes of intramembranous and endochondral ossification. Intramembranous ossification develops bone directly from connective tissue, while endochondral ossification replaces cartilaginous skeletal parts with bone. During endochondral ossification, hyaline cartilage is present near the epiphyses of long bones and breaks down as cartilage cell columns are replaced by osteoblasts depositing new bone tissue. Bone age can be determined by examining an x-ray of the epiphyseal plates and timing of their fusion with the diaphyses, which occurs at different ages for each bone.

1. Growth of bonesBone is mainly made up:Osteoblasts

2. Osteocytes

3. Osteoclasts

4. osteoid

5. inorganic saltsIn embryonic period bone model exists as cartilageEach bone has a different maturing period Periosteum covers all parts of bone for:Protection nourishment

6. Long bone growing in lengthLong bone growing in widthOsteoclasts remove bone tissueOsceocytes produce new bone tissue

7. Bone healingAfter fracture bone must be lined to original positionCallus is formed to hold bone in placeCallus made of collagenCallus calcifiesAnd absorbed and replaced by bone

8. Ossification Two types: intramembranous endochordralIntramembranous ossificationis the development of bone from connective tissueMesenchymal cells osteoblasts osteocyteOsteoclasts grow along, functioning in the removal and absorption of osseous tissueChondral ossification cartilaginous skeletal parts replaced by bone

9. Endochondral ossificationTwo types: Endochondral PerichondralEndochondral ossification near epiphyses (end of long bone)Hyaline cartilage present at articular surfacesCartilage cell columnsBreak down of cartilage replaced by osteoblastsPerichondral perichondrium at diaphysis

10. Bone ageCan be determined by studying epiphysis and diaphysis on x ray Disappearance of epiphyseal line fusionFusion occurs at different time for each boneThus, able to determine age